style: use monospace for changeset messages

Similar to commits 9005c37dbe21 and 6e65c2153baa that make PR descriptions
display in a monospace font, apply monospace on changeset messages.

Note that in the files template, the reference to the non-existing 'commit'
class can be replaced instead of appending to it.

kallithea/templates/changeset/changeset.html

@@ -133,7 +133,7 b''
                      % endif
                 </div>
             </div>
-            <div class="form-group">${h.urlify_text(c.changeset.message, c.repo_name)}</div>
+            <div class="form-group formatted-fixed">${h.urlify_text(c.changeset.message, c.repo_name)}</div>
             <div>
               <% a_rev, cs_rev, file_diff_data = c.changes[c.changeset.raw_id] %>
               % if c.limited_diff:

kallithea/templates/files/files_source.html

@@ -48,7 +48,7 b''
             ${h.gravatar_div(h.email_or_none(c.changeset.author), size=16)}
             <div title="${c.changeset.author}" class="user">${h.person(c.changeset.author)}</div>
       </div>
-      <div class="commit">${h.urlify_text(c.changeset.message,c.repo_name)}</div>
+      <div class="formatted-fixed">${h.urlify_text(c.changeset.message,c.repo_name)}</div>
     </div>
     <div class="panel-body no-padding">
       %if c.file.is_browser_compatible_image():

kallithea/tests/functional/test_files.py

@@ -102,7 +102,7 b' class TestFilesController(TestController'
                                     revision='8911406ad776fdd3d0b9932a2e89677e57405a48',
                                     f_path='vcs/nodes.py'))
 
-        response.mustcontain("""<div class="commit">Partially implemented <a class="issue-tracker-link" href="https://issues.example.com/vcs_test_hg/issue/16">#16</a>. filecontent/commit message/author/node name are safe_unicode now.<br/>"""
+        response.mustcontain("""<div class="formatted-fixed">Partially implemented <a class="issue-tracker-link" href="https://issues.example.com/vcs_test_hg/issue/16">#16</a>. filecontent/commit message/author/node name are safe_unicode now.<br/>"""
 """In addition some other __str__ are unicode as well<br/>"""
 """Added test for unicode<br/>"""
 """Improved test to clone into uniq repository.<br/>"""